re: living in the moment: because RAW sought to distance himself from the idioms of "New Age" and inspirational lit that tell us to "live in the moment" (and 97 other ways of working that), he seemed to couch his approach to that basic idea - an idea I find "wise" - in terms of zen, Korzybski, "Hedonic Engineering," and yogas. So, rather: philosophy that argues that we can only live in the present, so why not make it sexier, more fun, more inclusive, more interesting than yesterday's "reality"? Korzybski/zen/cannabis: all hover around the Event Level, which is pre-linguistic: try to observe w/o labels, remaining conscious that you're abstracting inevitably from the trillions of energies in the room, see if your perception of "reality" opens up something new to you. DOING, not preaching. This is RAW's pragmatism: it's easy for us to talk about living in the present, how worrying is neurotic and has about as much effect as throwing a glass of water over Niagara Falls, etc: "exercizes"! How to cop the gnosis? You actually put the book down and DO something in order to embody that state of feeling "in the moment."
Short answer: there's a crapload in RAW's oeuvre about forgiveness of one's past indiscretions/regret, the pragmatic benefits of optimism w/o being a "bliss ninny," and oodles of stuff, couched in various non-New Age sentences, that advise you to "Never Whistle While You're Pissing," which seems to me zen as all get-out.